Grey Friar vs mendicant

Grey Friar and mendicant both are nouns.

Word	Noun	Adjective	Verb	Adverb
Grey Friar	Yes	No	No	No
mendicant	Yes	Yes	No	No

As nouns, mendicant is a hypernym of Grey Friar; that is, mendicant is a word with a broader meaning than Grey Friar:

Grey Friar: a Roman Catholic friar wearing the grey habit of the Franciscan order
mendicant: a male member of a religious order that originally relied solely on alms

Other hypernyms of Grey Friar include friar.

Grey Friar (noun)	mendicant (noun)
a Roman Catholic friar wearing the grey habit of the Franciscan order	a pauper who lives by begging
	a male member of a religious order that originally relied solely on alms

Grey Friar (adjective)	mendicant (adjective)
	practicing beggary